For radio links, it is common to have packet domain and a radio link domain, where the radio link domain comprises the microwave radio and the antenna. The packet domain may be configured as an indoor part, and the radio link domain may be configured as an outdoor part.
Bonding means that different parts of the traffic are conveyed over different links and reassembled when received. If the links have different rates, the delays are different implying buffering before reassembly when waiting the subsequent parts of data to arrive over slower links. The link speed may also change arbitrarily between links due to e.g. different susceptibility to external conditions for different carrier frequencies. Buffering is therefore often centralized and need to be dimensioned for the worst use case.
Microwave hop protection means that at least two antennas are used to receive the same signal, transmitted from at least one transmitter. The received signal quality in different antennas may vary due to varying channel conditions over time, space and frequency. By selecting the best signal or combining signals from several antennas the hop becomes less susceptible to disturbances.
Bonding and protection are functions often configured together but implemented as different functions and at different protocol layer. This implies careful and thorough dimensioning and configuration of the system. Configuration often also becomes less intuitive.
Furthermore, bonding schemes create an overhead for bookkeeping since it is necessary to know the order of the part of data conveyed over different links when reassembling them. There are also tradeoffs to be made between e.g. buffering resources and segment size. For example, small segments reduce buffering requirements but increases overhead. The above is especially apparent when there is no bonding at all in 1+0 links (without protection). Often separate schemes are developed for this case and it is regarded as an exception when it really is the main use case.
Adding bookkeeping overhead as prefixes to data segments requires the complete segment to be buffered and analyzed before transmitted if the prefix contains references to data content. This creates additional store and forward delays in a system.
A QoS (Quality of Service) function in the packet domain is arranged to delete packets based on quality labeling when there is insufficient capacity over the links, where the insufficient capacity in this example is due to a certain data rate limitation in the radio link domain which then constitutes a so-called bottleneck. In order to support best operation of this function, it is important to minimize buffering between the QoS function and the present capacity bottleneck, since that may result in low priority packets being buffered in the radio link domain. When this buffer becomes filled, the QoS function is forced to delete high priority packets. When many radio links are bonded, this problem occurs since some buffering is necessary due to reordering emerging from rate differences, but that buffering often becomes unnecessarily large due to the latency introduced by long turn around times between packet and radio link domains.
In radio links, delays may vary with the momentary rate. This implies a problem when wanting to delay data for a certain time to compensate for rate differences in bonded hops.
It is therefore desired to provide an enhanced configuration of different devices in a wireless communication arrangement such as a radio link, and enhanced interface functionality between these devices.